1. Field of the Invention
The present invention relates to an image pickup apparatus which inputs an image and can be applied to a camera.
2. Related Background Art
In a conventional image pickup apparatus using solid state image pickup devices such as CCDs, MOSs, or the like, as shift pulses of horizontal and vertical shift registers, shift pulses of a predetermined period are outputted in accordance with an external timing signal. The image pickup apparatus receiving light of an object to be photographed sequentially reads out the solid state image pickup devices arranged two-dimensionally one line by line of horizontal lines, outputs as a time-sequential image pickup signal, scans the line that is lower than the horizontal line in the vertical direction by one line, sequentially reads out the image pickup signals, and subsequently scans, thereby obtaining one 2-dimensional image signal, and subsequently, reads out a number of 2-dimensional image signals, so that an image pickup signal as a motion picture can be obtained.
In the above conventional apparatus, however, an image pickup area, an image pickup frequency, and the like are decided by an image pickup sensor and a driving timing of a timing generator for driving such a sensor. Therefore, there is a case where only a partial image pickup portion in the image pickup signal inputted to the image pickup apparatus is needed. In this case, ordinarily, a focal point of a lens arranged in front of the image pickup sensor is changed and the direction of the image pickup apparatus is changed to the center of the necessary image pickup portion, and an object is photographed, an image pickup range is enlarged or reduced, thereby obtaining an image pickup signal of a necessary angle of field. However, it is extremely difficult to obtain only a desired area portion without changing the operation of the lens or the direction of the apparatus and there is no more effective means for obtaining such a desired area portion. For one image pickup sensor, operations such that the sensor can be driven by an optimum driving method, an image pickup area is selected, an image is picked up, an interlacing operation is performed, an image pickup frequency is varied, and the like cannot be performed.
It is an object of the invention that in one two-dimensional image pickup sensor, an image pickup frequency is varied and its optimum driving method is provided and that an image pickup apparatus in which an image pickup area is selectively photographed and an image pickup and an image pickup signal process of an invalid area can be omitted by an interlacing operation is provided.
According to the invention, there is provided an image pickup apparatus comprising: a two-dimensional solid state image pickup sensor from which pixel data instructed by horizontal and vertical shift registers is accessed and read out; and a timing generator for driving the two-dimensional image pickup sensor, wherein with respect to horizontal and vertical shift pulses which are supplied from the timing generator and which drive the horizontal and vertical shift registers of the 2-dimensional solid state image pickup sensor, periods of the horizontal and/or vertical shift pulses can be varied.
According to the invention, there is further provided area selecting means for selecting an arbitrary area, wherein when an area selected by the area selecting means is accessed, the periods of the horizontal and vertical shift pulses are extended and the horizontal and vertical shift registers are shifted at a low speed and, when an area which is not selected by the area selecting means is accessed, the periods of the horizontal and vertical shift pulses are reduced, the shift registers are shifted at a high speed, and the above operations are repeated at every vertical period.
According to the invention, there is further provided sampling and holding means for sampling and holding an output signal of the 2-dimensional solid state image pickup sensor, wherein when the area selected by the area selecting means is accessed, a sampling and holding pulse is inputted to the sampling and holding means and, when the area which is not selected by the area selecting means is accessed, the sampling and holding pulse is not inputted to the sampling and holding means.
The invention is characterized in that a plurality of periods of the horizontal and/or vertical shift pulses are prepared, among m horizontal shift pulses, n pulses (m denotes an integer that is equal to or larger than 1 and is equal to or less than the number of pixels of one line, n denotes an integer that is equal to or larger than 1 and is equal to or less than m) are set to pulses each having a long period and (mxe2x88x92n) pulses (including 0 pulse) are set to pulses each having a period shorter than that of the above n pulses, and among k vertical shift pulses, l pulses (k denotes an integer which is equal to or larger than 1 and is equal to or less than the number of lines of one picture plane, l denotes an integer which is equal to or larger than 1 and is equal to or less than k) are set to pulses each having a long period and (kxe2x88x92l) pulses (including 0 pulse) are set to pulses each having a period shorter than that of. the above l pulses, and the above-mentioned pulses are inputted to the 2-dimensional solid state image pickup sensor.
The invention is further characterized in that a plurality of periods of the horizontal and/or vertical shift pulses are prepared, among m horizontal shift pulses, n pulses (m denotes an integer that is equal to or larger than 1 and is equal to or less than the number of pixels of one line, n denotes an integer that is equal to or larger than 1 and is equal to or less than m) are set to pulses each having a long period and (mxe2x88x92n) pulses (including 0 pulse) are set to pulses each having a period shorter than that of the above n pulses, and among k vertical shift pulses, l pulses (k denotes an integer that is equal to or larger than 1 and is equal to or less than the number of lines of one picture plane, l denotes an integer that is equal to or larger than 1 and is equal to or less than k) are set to pulses each having a long period and (kxe2x88x92l) pulses (including 0 pulse) are set to pulses each having a period shorter than that of the above l pulses, and further, when the period of the vertical shift pulse is short, the horizontal shift pulse is not inputted.
According to the invention, there is further provided sampling and holding means for sampling and holding an output signal of the 2-dimensional solid state image pickup sensor, wherein a plurality of periods of the horizontal and/or vertical shift pulse are formed, among m horizontal shift pulses, n pulses (m denotes an integer that is equal to or larger than 1 and is equal to or less than the number of pixels of one line, n denotes an integer that is equal to or larger than 1 and is equal to or less than m) are set to pulses each having a long period, a sampling and holding pulse is inputted to the sampling and holding means, (mxe2x88x92n) horizontal shift pulses (including 0 pulse) are set to pulses each having a period shorter than that of the above n pulses, and the sampling and holding pulse is not inputted to the sampling and holding means.
The above and other objects and features of the present invention will become apparent from the following detailed description and the appended claims with reference to the accompanying drawings.